OK, pride-swallowing time.
I have an M4 with (what I am assuming to be) lead built up inside the bore. I have tried everything to get that crap out.
Yes, I have actual lead remover, and I have used mops, nylon brushes, bronze brushes, and patches to get that stuff out of there (I followed the instructions to a t). Crap is still in there, and thick.
All I have been shooting is #7 bird, 00 buck and some rifled slugs.
PLEASE, give this apparent amateur some guidance on getting that crap out. Thanks!